1. Field of the Invention
The present invention relates to a variable speed switch mounted to an electric power tool and capable of outputting an electric signal for increasing or decreasing an amount of power supplied to the motor of the electric power tool according to a displacement amount of a switch-operating portion.
2. Description on of the Related Art
An electric power tool is generally provided with a wake-up switch for limiting power consumption of a battery. Owing to the wake-up switch, a power source of a control circuit part of a motor is shut off while the electric power tool is not being used.
Japanese Laid-Open Patent Publication No, 2003-260675 discloses an electric power tool in which a wake-up switch (contact) is incorporated into a variable speed switch. More precisely, the variable speed switch includes a switch main body portion provided with a trigger that can be pulled with a finger, a slide type variable resistor configured to operate in conjunction with a pulling operation of the trigger, and a wake-up switch (contact) incorporated into the switch main body portion. And, as shown in FIG. 11, in a state in which the trigger is pulled by a fixed amount L0 against the force of a spring, the wake-up switch (contact) is turned on, and a voltage is applied to a control circuit part. In this state, when the trigger is further pulled, the resistance value of a variable resistor varies in proportion to the pulling amount and the amount of electric power supplied to the motor can be increased or decreased by the control circuit part as the resistance value varies.